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May 19, 2015 - A Look At The New Commandlinefu
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Commands using perl from sorted by
Terminal - Commands using perl - 345 results
perl -i -pe 'BEGIN{undef $/;} s/START.*?STOP/replace_string/smg' file_to_change
perl -MPOSIX -e 'print strerror($ARGV[0])."\n";' ERRNO
2011-09-21 18:16:19
User: sethjust
Functions: perl
Tags: strerror errno

Calls the POSIX strerror() function to look up the meaning of integer ERRNOs set by some functions.

tail -f LOGFILE | perl -ne '`say "$_"`;'
2011-09-16 05:33:22
User: tamouse
Functions: perl tail
Tags: perl tail say

say only processes a complete file, at eof, so following a file isn't possible. Quick and dirty perl oneliner to feed each line from the tail -f to say. Yes, expensive to lauch a new process each line.

This little ditty was prompted by a discussion on how horrible it is to use VoiceOver on ncurses programs such as irssi.

perl -MTerm::ReadLine -wde'print "TheAnswer=42\n"'
sudo find / -type f | perl -MFile::Basename -ne '$counts{dirname($_)}++; END { foreach $d (sort keys %counts) {printf("%d\t%s\n",$counts{$d},$d);} }'|sort -rn | tee /tmp/sortedfilecount.out | head
2011-09-14 19:41:19
User: tamouse
Functions: find perl sort sudo tee

Find which directories on your system contain a lot of files.

Edit: much shorter and betterer with -n switch.

cd /path/to/pmwiki/wiki.d;/bin/ls -1 | perl -ne 'my ($group,$name)=split(/\./);$counts{$group}++;' -e 'END { foreach $group (sort keys %counts) {printf("%d\t%s\n",$counts{$group},$group);} }'|sort -rn
2011-09-14 19:33:39
User: tamouse
Functions: cd perl sort
Tags: sort perl pmwiki

PmWiki stores wiki pages as Group.Name. Simply split the directory listing and count frequency of group occurances.

/usr/sbin/dmidecode | perl -lne 'print $1 if /Current\s+Speed:\s+(\d+\s+MHz)/'
route -n | perl -ne '$ANY=""; /^$ANY/ and split /\s+/ and print "Gateway to the World: ",($_[1]!=$ANY)?$_[1]:(`ip address show $_[$#_]`=~/peer ([0-9\.]+)/ and $1),", via $_[$#_].\n"'
perl -ne '$. == 4 && print && exit'
2011-09-05 21:52:16
User: bashrc
Functions: perl

Perl version - just for completeness sake ;)

cat file.csv | perl -pe 'if($. == 1) {@h = split(/;/); $i = 1 ; map { $_ = $i; $i++ } @h; print join(" ;", @h) , "\n"} ; s/(^|;);/$1 ;/g' | column -ts\; | less -S
perl -F'\s+' -anE 'push @w,$F[1];END{$r.=splice @w,rand @w,1 for(1..4);say $r}' diceware.wordlist.asc
echo "LINUX,DIR,FILE1,FILE2,FILE3" | perl -aF, -nle 'my ($fld1, $fld2, @fields) = @F; while(@fields) { print join ",", $fld1, $fld2, splice(@fields, 0, 1) }'
2011-08-22 18:27:12
User: mindrape
Functions: echo join perl

Lets say you have a file with the following layout:


You want the file to look like this:




This perl command does it for you.

perl -ne 'print "$1 " if /^Host (.+)$/' ~/.ssh/config
2011-08-21 14:51:20
User: bashrc
Functions: perl

I use this in my bashrc to expand hosts defined in ~/.ssh/config:

function _ssh_completion() {

perl -ne 'print "$1 " if /^Host (.+)$/' ~/.ssh/config


complete -W "$(_ssh_completion)" ssh

Here's a great article on how to setup your own ~/.ssh/config:


find /var/spool/mqueue -type f -mtime +7 | perl -lne unlink
2011-08-19 15:22:02
User: mengesb
Functions: find perl

Find all files in /var/spool/mqueue older than 7 days, pass to perl to efficiently delete them (faster than xargs or -exec when you've got millions or hundreds of thousands to delete). Naturally the type, directory, and file age vars can be adjusted to meet your specific needs.

strace -ff -e trace=file my_command 2>&1 | perl -ne 's/^[^"]+"(([^\\"]|\\[\\"nt])*)".*/$1/ && print'
2011-08-16 15:00:18
Functions: perl strace

Can be run as a script `ftrace` if my_command is substrituted with "[email protected]"

It is useful when running a command that fails and you have the feeling it is accessing a file you are not aware of.

prep () { perl -nle 'print if '"$1"';' $2 }
2011-08-13 14:29:26
User: dbbolton
Functions: perl
Tags: perl grep regex

If you've ever tried "grep -P" you know how terrible it is. Even the man page describes it as "highly experimental". This function will let you 'grep' pipes and files using Perl syntax for regular expressions.

The first argument is the pattern, e.g. '/foo/'. The second argument is a filename (optional).

cat subtitles.txt | perl -pe 's/} /}/g; s/{(\d+)}/=1=/; $f1=(24/25*$1); s/{(\d+)}/=2=/; $f2=(24/25*$1); $f1=~s/\..*//; $f2=~s/\..*//; s/=1=/{$f1}/; s/=2=/{$f2}/; ' > subtitles_newfps.txt
2011-07-30 15:34:43
User: ciekawy
Functions: cat perl

this command example converts to 25 fps subtitles that were originally created for 24 fps movie

perl -mText::Highlight -E 'say Text::Highlight->new(ansi => 1)->highlight(Perl => do { local (@ARGV,$/) = shift; <> }) ' path/to/perl-file.pl
perl -ne 'print if m{\Q/*\E}x .. m{\Q*/\E}x or m{\/\/}x' *.c
2011-07-12 04:41:49
User: dbr
Functions: perl

more idiomatic version of the same, using the flip-flop-operator; also printing lines with '//'-style comments

arp-scan -I eth0 -l | perl -ne '/((\d{1,3}\.){3}\d{1,3})/ and $ip=$1 and $_=`nmblookup -A $ip` and /([[:alnum:]-]+)\s+<00>[^<]+<ACTIVE>/m and printf "%15s %s\n",$ip,$1'
perl -e 'my $in_comment = 0; while (<>) { $in_comment = 1 if m{\Q/*\E}; print if $in_comment; $in_comment = 0 if m{\Q*/\E}; }' *.cpp
2011-07-08 00:17:27
User: doherty
Functions: perl

This is a naive way of finding source code comments in source code files that use C-like comments: // and /*...*/

tail -f /var/log/squid/access.log | perl -p -e 's/^([0-9]*)/"[".localtime($1)."]"/e'
tail -f /var/log/logfile|perl -e 'while (<>) {$l++;if (time > $e) {$e=time;print "$l\n";$l=0}}'
2011-06-21 10:28:26
User: madsen
Functions: perl tail time
Tags: perl tail

Using tail to follow and standard perl to count and print the lps when lines are written to the logfile.

perl -MFile::Find -e"finddepth(sub{rmdir},'.')"
perl -MFile::Find -e"finddepth(sub{rmdir},'.')"
2011-05-23 08:45:34
User: igorfu
Functions: perl
Tags: perl delete

Recursively delete empty directories. Use with care.